Building czmq on MSVC

CZMQ, the high level C binding for ØMQ, is available for download from the zeromq.org official page, currently in version 1.1.0. The problem is that, if you want to use it for Visual Studio, there are a few issues.

Firstly, the zip file currently available misses some stuff, most notably, the solution files for MSVC. You can overcome this, getting the latest czmq version from github:

git clone git://github.com/zeromq/czmq

Next step is compiling it, and, as one should expect, the czmq source code includes references to zeromq. You can get it from here:

git clone git://github.com/zeromq/zeromq2-x

Now you are ready to open the czmq solution in the win32 subfolder. Ensure in the project - properties that the relation to zeromq is carried on correctly.

Compile it. If no changes occurred from when I have written this post, compiling for MSVC2010 you should get a few errors:

1>..\src\zframe.c(461): error C2440: 'initializing' : cannot convert from 'void *' to 'char *'
1>..\src\zmsg.c(194): error C2440: 'initializing' : cannot convert from 'void *' to 'zframe_t *'
1>..\src\zmsg.c(503): error C2440: '=' : cannot convert from 'void *' to 'byte *'
1>..\src\zmsg.c(772): error C2440: 'initializing' : cannot convert from 'void *' to 'byte *'
1>..\src\zsockopt.c(138): error C2440: 'initializing' : cannot convert from 'void *' to 'char *'

Explicit cast are required, patch the code like this:

// zframe.c:461
char *buffer = static_cast<char*>(malloc(1024));

// zmsg.c:194
zframe_t *frame = static_cast<zframe_t *>(zlist_pop (self->frames));

// zmsg.c:503
*buffer = static_cast<byte *>(malloc (buffer_size));

// zmsg.c:772
byte *blank = static_cast<byte *>(zmalloc (100000));

// zsockopt.c:138
char *identity = static_cast<char*>(zmalloc (option_len));

Once corrected these errors, you should complete correctly the czmq project, producing czmq.lib in the win32 folder.

Create a project that uses zmq and czmq, setting properly include and library directories, and a reference to the actual lib files among the linker additional dependencies.

Finally you can write a first tiny hello czmq application that just instantiate and destroy a zmq context:

#include <czmq.h>

// ...
{
    zctx_t* ctx = zctx_new();
    assert(ctx);
    zctx_destroy(&ctx);
    assert(ctx == NULL);
}